In our original example, the radial bearing is not given but it is S28d45'21W. This line will run from the last endpoint to the center point of the next curve. If you are given a radial bearing, you can use this to lay out a non-tangent curve also.
The Radial Bearing is the bearing from the start point of the curve to the radius point of the curve. Use this same technique for non-tangent curves. If the curve is opposite of what you expect, select the start and end points in the opposite order. _ARC command and select the start point, then choose the "E" option and pick the end point, then use the "R" option and enter the radius. The string you will use is you have this line, you can draw the curve. So now, draw a line that represents this Chord Bearing, using the same syntax as above.
Remember, the Chord Bearing is the bearing from the start point to the end point so in this case, the Chord Bearing is in the SE direction, not NE. Depending on the direction you are traversing a figure, you may need to reverse bearings by 180 degrees. Is the other end of this curve really in the NW direction? No. Going back to the first curve in the figure above, we can see that the Chord Bearing is N30D57'08"W. The Chord Bearing is the bearing from the start point of the curve to the end point of the curve. You can use either the Chord Bearing and Chord Distance or you can use the Radial Bearing. This is the case for non-tangent curves in the middle of a figure or if you want to start your figure with a curve. The orientation of tangent curves is determined by the previous entity, but for non-tangent curves you need to know how the curve is oriented. _LINE command and pick the endpoint of the last arc, then enter Non-Tangent curves The last line segment is constructed just like the first two. Now you have your three points from which you can construct the arc. Now it should look like the picture below (the radius point is not shown since it is so far away). Because this curve is to the left, the rotation angle will be positive, not negative. Now rotate this line the amount of the delta, just like before. The other end is the center point for the next curve. _LENGTHEN command to make this line 500 foot long (the radius of this curve). Now trim off the part that is inside the previous curve. In this case we already have the green line in place, so extend it out past the last curve a bit. We need to do the same as above to find the center point, except rather than draw a perpendicular line, we need to draw a radial line from the previous curve. Notice that this curve is to the left, not the right, so this is a reverse curve. If the second curve goes in the same direction, it's called a compound curve, if the second curve goes in the opposite direction, it's called a reverse curve. This curve is also tangent, but in this case the previous entity is a curve. Next pick the endpoint of the previous line segment. Next pick the other endpoint of the line, that is the startpoint of the ARC. _ARC command, enter "C" for center point and pick the endpoint of the line that represents the center point. Now you have the three points needed to draw the ARC. Since this curve is to the right, rotate the line clockwise (meaning you will have to enter a negative angle) the amount of the delta of the curve. Now rotate this line, using the opposite endpoint as the radius point. The image below is how it should look now (the green line is the new one). The opposite endpoint is the center point for the next curve. _LENGTHEN command to set the exact length. Make this line the same length as the radius of the curve.
We will assume that this curve is tangent to the previous segment (we'll cover non-tangent curves later).ĭraw a line perpendicular to the previous segment towards the inside of the curve.
_LINE command because you need to draw a curve next. Then at the next prompt enter stay in the line command and draw the next segment. If you have XY or Northing and Easting coordinates, you can enter them, otherwise just pick any point in the drawing. Let's start in the lower left (or most southwesterly) corner and work clockwise for this example.įor each line segment, a bearing and distance is given. Start with a line segment if there is one. Below is an example of what you might have. Let's say you have a paper plot or a legal description of a closed boundary. If you have a civil/survey program or add-on, such as Land Desktop, SurvCADD, Eagle Point, etc., then there are built-in tools for entering lines and curves. These techniques apply to basic CAD programs such as AutoCAD, IntelliCAD, etc.
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